This invention relates to ink jet printheads. More particularly, this invention relates to a nozzle arrangement for an ink jet printhead, the nozzle arrangement including a volume-reducing actuator.
The Applicant has invented an ink jet printhead that is capable of generating text and images at a resolution of up to 1600 dpi.
In order to achieve this, the Applicant has made extensive use of micro electro-mechanical systems technology. In particular, the Applicant has developed integrated circuit fabrication techniques suitable for the manufacture of such printheads.
The printheads developed by the Applicant can include up to 84000 nozzle arrangements. Each nozzle arrangement has at least one moving component which serves to eject ink from a nozzle chamber. These components usually either act directly on the ink or act on a closure which serves to permit or inhibit the ejection of ink from the nozzle chamber.
The printheads are manufactured in accordance with an integrated circuit fabrication technique. It follows that the moving components are microscopically dimensioned. This is necessary, given the large number of nozzles per printhead.
Applicant has spent a substantial amount of time developing such moving components in the form of actuators which move within each nozzle chamber to eject ink from the nozzle chamber. A particular difficulty that must be overcome is to achieve sufficient movement of an actuator within the nozzle chamber not only to eject ink but also to ensure that the ink is separated from the remainder of the ink in the chamber to form an ink drop. It follows that sufficient momentum must be imparted to the ink and then directly followed by a reduction in ink pressure in order to create necking of the ink which has been ejected and consequent separation to form an ink drop.
Applicant has conceived the present invention in an attempt to achieve efficient ink ejection and subsequent necking and separation to form the drop.
According to a first aspect of the invention there is provided a nozzle arrangement for an ink jet printhead, the nozzle arrangement comprising
a substrate;
a roof wall, side walls and a floor that define a nozzle chamber; and
an actuator that is arranged on the substrate for facilitating the ejection of ink from the nozzle chamber of the nozzle arrangement, the actuator comprising
at least one actuating member that is mounted on the substrate and is operatively positioned with respect to the nozzle chamber to define at least part of one of the roof wall, floor and side walls of the nozzle chamber, the, or each, actuating member being displaceable between an inoperative condition and an operative condition to reduce a volume of the nozzle chamber so that ink is ejected from the nozzle chamber; and
an actuating mechanism for displacing the, or each, actuating member between the inoperative and operative conditions.
According to a second aspect of the invention, there is provided an ink jet printhead which comprises
a substrate;
a plurality of nozzle arrangements positioned on the substrate, each nozzle arrangement comprising
a roof wall, side walls and a floor that define a nozzle chamber; and
an actuator that is arranged on the substrate for facilitating the ejection of ink from the nozzle chamber of the nozzle arrangement, the actuator comprising
at least one actuating member that is mounted on the substrate and is operatively positioned with respect to the nozzle chamber to define at least part of one of the roof wall, floor and side walls of the nozzle chamber, the, or each, actuating member being displaceable between an inoperative condition and an operative condition to reduce a volume of the nozzle chamber so that ink is ejected from the nozzle chamber; and
an actuating mechanism for displacing the, or each, actuating member between the inoperative and operative conditions.
The invention is now described, by way of examples, with reference to the accompanying drawings. The specific nature of the following description should not be construed as limiting in any way the broad scope of this summary.